The Neurophysiological Biomarker Toolbox (NBT)

Select type of test and display

We now choose the type of statistical test that we would like to perform on the data and how we would like it displayed.

Spearman correlation

If Spearman correlation is selected then the results shown will be the Spearman rank correlation coefficient between the two biomarkers.

Here, we can see the correlation for one group between the ARSQ factor Somatic and the normalized alpha.

TTest after splitting on biomarker

If TTest after splitting is selected, then the data is split into two groups based on the splitting type and value picked. A T-test is then performed between the groups using the comparison biomarker. The result will tell you whether the two groups are significantly different in respect to the comparison biomarker.

We also have two options of how to display the results.

Individual channels

If individual channels is picked then the result is a grid of significance values (p-values). On the x-axis is the splitting biomarker and on the y-axis is the comparison biomarker. Each each grid cell shows whether there is a significant correlation between the EEG biomarker for a certain channel (or region) and a certain ARSQ item (or dimension).

If you right-click on an ARSQ item then you get the topoplots for both types of test:

On the left you can see the p and rho values for each region between ARSQ item 56 (Somatic) and Normalized alpha power. On the right there are four plots. The left column has two topoplots showing the mean normalized alpha powers for the top and bottom 30% groups based on the ARSQ score to item 56. The middle column shows the p-values for the unpaired ttest between these groups, and the right column shows the difference in means between these groups showing that the top group has lower normalized alpha power in all regions compared to the bottom group

If you right click on one of the cells then you can see the correlations for the two different tests as shown above when describing the tests.


If topoplots is picked then the result will show the same data as the grid, but in a topoplot form. Next to the significance topoplot will be another topoplot indicating the direction of the correlation (for Spearman this will be the rho value, and for ttest after splitting this will be the difference in mean between the two groups.


tutorial/comparebiomarkersselecttypeoftest.txt · Last modified: 2015/05/27 15:50 by Sonja Simpraga
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